Walnut tree names &#39;wolfskill&#39;

ABSTRACT

A new walnut variety ( Juglans regia ) designated as ‘UC Wolfskill’ is provided. This variety has a harvest date 10 days earlier than walnut variety ‘Chandler’ and produces a walnut that is jumbo in size with light colored kernels.

Latin name: Botanical/commercial classification: Juglans regia, newEnglish walnut tree cultivar.

Tree denomination: The variety denomination of the claimed walnutvariety is ‘UC Wolfskill’.

BACKGROUND OF INVENTION

It has long been recognized as desirable to provide walnut trees bearinglarge crops that are ripe for commercial harvesting and shipment earlyin the harvest season. In particular, the California walnut industry isin need of earlier harvesting walnut varieties, as the most commonlyplanted variety ‘Chandler’ (U.S. Plant Pat. No. 4,388) harvests late inthe season (early to mid-October), which delays processing. Further, thewalnut industry desires walnut cultivars with light kernel color formarketing value. Thus, there exists a need for improved walnut varietieswith mid-season harvest dates and desirable walnut characteristics. Thetree of the present cultivar, ‘UC Wolfskill’, produces a nut that hashigh quality but is ready for harvest approximately 10 days before‘Chandler’, about the same time as the reference cultivar ‘Solano’ (U.S.Plant Pat. No. 25,466).

BRIEF SUMMARY OF THE INVENTION

The present invention relates to a new and distinct cultivar of walnuttree (Juglans regia) that has been denominated as ‘UC Wolfskill’ andmore particularly to a walnut tree that has a harvest date 10 daysearlier than the walnut tree cultivar ‘Chandler’ and that furtherproduces a walnut that is jumbo in size with light colored kernels.

It was found that the new Juglans regia cultivar of the presentinvention exhibits the following combination of characteristics:

-   -   a) forms jumbo-sized walnuts that possess extra light-colored        kernels;    -   b) bears well-filled nuts with shells that are light colored,        relatively thin, and attractive in appearance;    -   c) bears fruit both terminally and laterally;    -   d) yields a crop that can be harvested approximately 10 days        before ‘Chandler’; and    -   e) is protandrous, bearing male flowers before female flowers.

The new Juglans regia walnut tree of the present invention was createdat Davis, Calif. in Year 1 by a controlled pollination between‘Chandler’ and ‘Solano’. The breeding pedigree is shown in FIG. 1.

Seeds from the cross were planted and the resulting 5282 trees werecarefully observed along with other trees in the walnut breedingprogram. When they began to bear nuts, data were collected annually onleafing date, first, peak and last female flower bloom, first, peak andlast male bloom, blight severity and yield. Nuts were sampled, cracked,and data was collected on shell appearance, shell thickness, shellintegrity, shell strength, nut weight, kernel weight, percent kernel,ease of kernel removal, kernel color, and percent kernel shrivel. Asingle tree was selected from among progeny of this controlled crossbased on its superior attributes. This selection was originallydesignated ‘UC03-001-2357’ and is now designated the ‘UC Wolfskill’cultivar after John R. Wolfskill, an early pioneer in Californiahorticulture. Compared to ‘UC Wolfskill’, the male parent ‘Solano’ hassimilar phenology but fewer extra light kernels; the female parent‘Chandler’ is later harvesting than ‘UC Wolfskill’ and nuts have a lowerpercent kernel fill (TABLE 2).

The new cultivar of the present invention has been asexually propagatedby grafting on ‘Paradox’ rootstock in selection blocks at Davis and ingrower field trials at Woodland, Durham, Wheatland, Red Bluff, Rio Oso,Merced, and Crow's Landing Calif., and at major California walnutnurseries. The distinctive characteristics of the new cultivar have beenfound to be stable and are transmitted to the new trees when asexuallypropagated.

BRIEF DESCRIPTION OF THE TABLES

TABLE 1 shows trial locations, number of trees at each site, and numberof years of data collected at each location.

TABLE 2 shows summarized phenology, tree, and nut evaluations for ‘UCWolfskill’, both parents, and several comparison cultivars.

TABLE 3 shows a key to evaluation traits presented in TABLE 2.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the breeding pedigree of the ‘UC Wolfskill’ walnut.

FIG. 2 shows a tree of ‘UC Wolfskill’ walnut at 7 years.

FIG. 3 shows bark of ‘UC Wolfskill’ walnut.

FIG. 4 shows adaxial view of leaf of ‘UC Wolfskill’ walnut.

FIG. 5 shows abaxial view of leaf of ‘UC Wolfskill’ walnut.

FIG. 6 shows female flowers of ‘UC Wolfskill’ walnut.

FIG. 7 shows catkins (male flowers) of ‘UC Wolfskill’ walnut

FIG. 8 shows hulls of ‘UC Wolfskill’ walnut.

FIG. 9 shows nuts of ‘UC Wolfskill’ walnut.

FIG. 10A shows a comparison of the kernels of ‘UC Wolfskill’ walnut toother walnut cultivars (the kernels of ‘UC Wolfskill’ is shown in thecolumn indicated by the arrow).

FIG. 10B shows nuts and kernels of ‘UC Wolfskill’ walnut.

DETAILED BOTANICAL DESCRIPTION

The description is based on an ungrafted walnut tree on its own rootsand trees subsequently grafted on ‘Paradox’ rootstock growing inselection blocks at Davis, and grower trials near Woodland, Durham,Merced, Wheatland, and Rio Oso, Calif. Data were collected on the ownrooted tree from Year 5 (age 3 years) to Year 15 (age 13 years). Datafrom Year 9 to Year 17 were collected from grafted trees. The MunsellColor Charts for Plant Tissues (GretagMacbeth LLC, 617 Little BritainRoad, New Windsor, N.Y. 12553-6148) is used in the identification ofcolor. Also, common color terms are to be accorded their ordinarydictionary significance.

Botanical classification: Juglans regia Female parent: ‘Chandler’ Maleparent: ‘Solano’.

-   Plant: The growth habit of the plant is illustrated in FIG. 2. This    7 year old tree is approximately 6.85 meters in height with a canopy    diameter of 6.2 meters. The trunk diameter at 0.5 meters above the    ground is approximately 19 cm. The silvery grey bark is typical of    Juglans regia. The young bark is brown (5Y 7/2) and the older bark    is grey (2.5Y 8/2) with raised lighter lenticels (5YR 8/2) (FIG. 3).    Lenticels are round to oval in shape, 1-5 mm×1-2 mm in size. ‘UC    Wolfskill’ has vigor similar to ‘Chandler’.-   Foliage: The dark green foliage is illustrated in FIG. 4 and FIG. 5    and is typical of Juglans regia. Leafing out date between Year 6 and    Year 17 has occurred on March 27^(th) on the average. For    comparative purposes, the ‘Chandler’ cultivar leaf-out is April    5^(th). The typical leaf coloration is green (adaxial 7.5GY 4/4,    abaxial 5GY 5/2). The leaves are pinnately compound with 7-9    leaflets. The full leaf length is approximately 39 cm. and width is    27 cm. Leaflets are broadly elliptical and entire. The terminal    leaflet averages 17 cm in length and 8 cm in width. The middle    leaflets average 13 cm in length and 6 cm in width and the proximal    leaflets average 8 cm in length and 4 cm in width. The rachis    averages 30 cm in length and 2-4 mm in diameter. Petiole length is    10 cm and is 2.5GY 8/8 in color.-   Inflorescence: The tree is precocious with first yield being noted    at age 3 years. Male flowers (catkins) were first present at age 4    years. This delay in male maturity is typical of Juglans regia. From    Year 6 to Year 17, average first female bloom occurred on April 11,    peak bloom on April 14 and last bloom on April 18. From Year 6 to    Year 17, average male flowering (pollen shedding) began March 28,    peaked on April 4 and terminated April 10. Pollen shedding in this    protandrous variety does not cover pistillate bloom well, suggesting    that a pollinizer could be helpful for maximum yield. ‘Chandler’,    ‘Howard’ (U.S. Plant Pat. No. 4,405), or ‘Tulare’ (U.S. Plant Pat.    No. 8,268) would be satisfactory pollinizers. The female flowers are    typical of Juglans regia (FIG. 6) with two flowers per inflorescence    borne on 1 cm spikes at both terminal and lateral positions on    current season's growth. Approximately 97% of the lateral buds    contain inflorescences, making yields much greater than trees that    only bear flowers terminally. A typical female flower is    approximately 8 to 10 mm at anthesis and floral organs are typical    of J. regia. The flowers appear vase-shaped when the 2 plumose    stigmatic arms are curved outward. There are no petals. The female    flowers are green (5GY 7/8) in color. The flower fragrance is    typical of J. regia and is not noticeably different from the foliage    fragrance. The male flowers (FIG. 7) are borne on catkins, between 7    and 14 cm in length and 1-2 cm in diameter, and are green in color    (5GY 7/10).-   Walnuts: The new cultivar commonly harvests about 10 days before    ‘Chandler’, about 13 days after ‘Payne’ (unpatented), and is similar    in timing to ‘Solano’. The new cultivar has excellent yields of    mostly jumbo-sized walnuts. The hull is broadly elliptic, 5.1 cm×4.6    cm, 7 mm thick, and 7.5GY 7/4 in color with numerous lighter    speckles (FIG. 8). The nut is broadly ovate, has a lightly grooved    shell, is a light tan color (7.5YR 6/4) and measures approximately    40 mm in length and 34 mm in width (FIG. 9). The shell is 1.2 mm    thick, average strength and well-sealed, and the kernel is easy to    remove. The kernel weight averages 8.1 g and makes up 58% of the    total nut weight of 14.1 g. Kernel color is considered excellent    (FIG. 10) and scores mostly in the light to extra light categories    (i.e.; 33% extra light, 57.4% light, 9.8% light amber, and 0% amber)    of the USDA Standards for Grades of Shelled Walnuts as determined by    using the standard Walnut Color Chart for kernels published by the    Dried Fruit Association of California (TABLE 2). In addition,    kernels of ‘UC Wolfskill’ have averaged 57.1 on the Relative Light    Index used by Diamond Foods of Stockton, Calif. It is typical of    commercial walnuts in terms of flavor and firmness.-   Disease susceptibility: This cultivar appears have somewhat lower    incidence of blight (Xanthomonas arboricola pv. juglandis) than    other cultivars with comparable leafing dates.-   Usage: This new cultivar of the present invention provides a    mid-season walnut with high quality light-colored kernels,    harvesting earlier than ‘Chandler’ with greater kernel fill and    similar kernel color and shell traits.

TABLE 1 Trial sites, locations, number of trees at location, and yearsof evaluation data collected for ‘UC Wolfskill’. # Years Year # Trees ofData Comparison Culti- Plant- Eval- Col- vars Evaluated at Location eduated lected Same Location Trial Site UC Davis - Davis Year 3 1 11Chandler, Solano, North Durham (U.S. Seedling Plant Pat. Block No.28,529), Tulare, Vina, Howard, Ivanhoe UCD Davis Year 8 4 8 Chandler,Solano, Selection Durham, Tulare, Block D Vina, Howard, IvanhoeScheuring Wood- Year 8 4 9 Chandler, Solano, S505 C land Durham, Tulare,Vina, Howard, Ivanhoe Stolp D Durham Year 8 4 8 Chandler, Solano,Durham, Tulare, Howard, Ivanhoe Whitney Wheat- Year 8 4 6 Chandler,Solano, Warren land Howard, Tulare, Ranch A Hartley, Vina, Norene B RioOso Year 20 4 Chandler, Solano, 12 Durham, 03-001-1372 Crane Merced Year11 2 Chandler, Solano, 12 Durham, Tulare, 03-001-1938, 03- 001-1457, 06-005-31 Gilbert B Wheat- Year 55 3 Chandler, Solano, land 14 Dur-ham,03-001- 1938, 03-001-1372, 03-001-2440, 06-005-31 Orestimba Crow's Year~50 observa- Chandler, Solano, Nursery Landing 14 tional Tulare, 03-001-1372, 03-001- 1938, 03-001- 2440, 00-006-227 Norene C Rio Oso Year ~500new Chandler, Solano, 17 Durham, Tulare, Howard, Vina, 03-001-1372Nursery Locations Sierra Gold Yuba Year nursery for increase NurseryCity 14 Burchell Oakdale Year nursery for increase Nursery 14 DaveWilson Hughson Year nursery for increase Nursery 15 Venice Hills VisaliaYear nursery for increase Nursery 18

TABLE 2 Performance of ‘UC Wolfskill’ compared to its parents andsimilar cultivars - means and standard errors for all locations Year 5to Year 17. Year- locations Trait (units) evaluated UWolfskill ChandlerSolano Leafing 14 3/26 ± 1.5 4/6 ± 1.6 3/25 ± 1.5 date (days) Pollenshed 13 4/4 ± 1.7 4/13 ± 1.3 4/3 ± 1.3 date (days) Female 13 4/14 ± 1.74/22 ± 1.1 4/11 ± 1.3 bloom date (days) Harvest date 17 9/26 ± 1.7 10/6± 1.1 9/20 ± 1.9 (days) Yield (0-9 19 7.3 ± 0.1 6.5 ± 0.1 7.2 ± 0.1scale) Blight (0-9 13 1.1 ± 0.5 0.9 ± 0.3 2.4 ± 0.5 scale) Inshell 3414.0 ± 0.2 12.9 ± 0.3 14.7 ± 0.3 weight (g) Kernel 34 8.2 ± 0.2 6.4 ±0.2 8.0 ± 0.2 weight (g) Percent 34 58.4 ± 0.5 50.0 ± 0.5 54.5 ± 0.4kernel (%) Ease of 34 4.5 ± 0.1 3.8 ± 0.1 4.5 ± 0.1 removal (0-9 scale)Percent 34 68 ± 5 70 ± 5 50 ± 6 extra light (%) Percent 34 30 ± 4 25 ± 446 ± 6 light (%) Percent 34 1 ± 1 5 ± 2 4 ± 2 light amber (%) Percent 344 ± 1 28 ± 3 8 ± 3 tip shrivel (%) Durham U.S. Vina Plant (not Pat. No.Trait (units) patented) Howard Tulare 28,529 Leafing 3/27 ± 1.7 4/6 ±28,529 4/3 ± 1.9 3/30 ± 1.9 date (days) Pollen shed 4/5 ± 1.5 4/10 ± 1.54/12 ± 1.6 4/6 ± 1.4 date (days) Female 4/12 ± 1.4 4/20 ± 1.3 4/17 ± 1.54/16 ± 1.4 bloom date (days) Harvest date 9/22 ± 1.2 9/27 ± 1.4 9/28 ±1.7 9/24 ± 1.0 (days) Yield (0-9 7.1 ± 0.1 6.9 ± 0.1 7.3 ± 0.1 6.6 ± 0.2scale) Blight (0-9 3.9 ± 0.6 0.6 ± 0.3 1.6 ± 0.7 0.2 ± 0.2 scale)Inshell 13.9 ± 0.5 13.4 ± 0.4 13.9 ± 0.4 15.1 ± 0.2 weight (g) Kernel7.0 ± 0.3 6.8 ± 0.2 7.6 ± 0.2 8.4 ± 0.2 weight (g) Percent 50.4 ± 0.550.9 ± 0.3 54.2 ± 0.5 55.3 ± 0.4 kernel (%) Ease of 5.1 ± 0.1 4.6 ± 0.14.5± 0.1 4.2 ± 0.1 removal (0-9 scale) Percent 1 ± 1 16 ± 4 6 ± 3 47 ±6   extra light (%) Percent 42 ± 9 69 ± 5 80 ± 4 49 ± 6   light (%)Percent 56 ± 9 15 ± 4 13 ± 4 3 ± 1   light amber (%) Percent 0 ± 0 3 ± 18 ± 2 19 ± 4   tip shrivel (%)

TABLE 3 Key to evaluation traits presented in TABLE 2. Tree evaluationCatkin abundance Male flower abundance: 3 low; 5 intermediate; 7 highFemale abundance Female flower abundance: 3 low; 5 intermediate; 7 highLateral Percent of lateral buds with female flowers fruitfulness % YieldYield: 3 low; 5 intermediate; 7 high Nut and kernel traits Texture Shelltexture: 3 smooth; 5 medium; 7 rough Color Shell color: 3 light; 5medium; 7 dark Seal Shell seal: 3 weak; 5 intermediate; 7 strongStrength Shell strength: 3 weak; 5 intermediate; 7 strong IntegrityShell integrity: 3 substantial area of shell missing; 5 small area ofmissing shell; 6 stem end hole; 7 complete shell Thickness Shellthickness at mid-cheek in mm Packing tissue Inner lining: 3 thin; 5medium; 7 thick Inshell weight g Kernel weight g Kernel % Kernelwt/inshell wt × 100 Fill Kernel fill: 3 poor; 5 moderate; 7 wellPlumpness Kernel plumpness: 3 thin; 5 moderate; 7 plump Ease of removalEase of removal of kernel halves: 3 easy; 5 moderate; 7 difficult Blanks% Percent of nuts without a kernel Extra light % Percent of kernels inextra light category (DFA*) Light % Percent of kernels in light category(DFA) Light amber % Percent of kernels in light amber category (DFA)Amber % Percent of kernels in amber category (DFA) Tip shrivel % Percentof kernels with tip shrivel like Chandler <50% shrivel Percent ofkernels with <50% shrivel >50% shrivel Percent of kernels with >50%shrivel Veins % Percent of kernels with conspicuous veins *“DFA” refersto Dried Fruit Association of CA

What is claimed is:
 1. A new and distinct variety of walnut treedesignated ‘UC Wolfskill’ as shown and described herein.